A leading neuroscientist explains why consciousness is intrinsic causal power rather than computation, and how a shattering psychedelic trip challenged his view of the mind.
The Dissolution of the Self
In three deep breaths, the field of vision shattered into dark hexagons. There was no time to take a fourth breath before plunging into what felt like a black hole. Memory vanished, time ceased to pass, and the personal identity of Christof Koch fell away completely. What remained was blinding light, terror, and pure ecstasy. The entire encounter lasted perhaps nine minutes on an ordinary clock, yet it felt utterly timeless.
For a scientist who spent four decades investigating the neural correlates of consciousness alongside pioneers like Francis Crick, this 5-MeO-DMT journey provided direct experiential evidence for a radical truth. Consciousness does not require self-consciousness. Modern humans often mistake their running inner monologue and personal history for awareness itself. Yet when every trace of personal identity is wiped out, awareness does not turn off. Absolute subjective experience remains.
Consciousness Is Not Computation
Most current artificial intelligence research relies on a metaphysical belief called computational functionalism. This view assumes that if a machine performs the right functional steps, subjective feelings must emerge. Integrated Information Theory, developed by Giulio Tononi and expanded by Koch, reaches the opposite conclusion. Consciousness is not an algorithm running on digital hardware. A computer program can mimic every word an intelligent person says, but it remains dark inside.
Koch points to an astrophysicist simulating Einstein's field equations for a supermassive black hole. The code tracks space, time, and stellar orbits with perfect mathematical accuracy. Yet the computer programmer never fears getting sucked into the terminal screen. A simulation of gravity exerts no real gravitational pull. In the same way, simulating the causal behavior of brain circuits in digital code does not constitute real awareness. You cannot compute consciousness into existence. You must build a physical architecture that possesses the causal power itself.
Measuring Intrinsic Causal Power
Integrated Information Theory begins with René Descartes and the only certainty we have: direct conscious experience exists. Every experience has specific properties. It is intrinsic, existing only for the subject. It is differentiated, because a toothache feels entirely unlike looking at a snowy landscape. It is also integrated into a single unified whole. When you look at an empty room, you do not experience separate, fragmented pieces of left and right. You experience one unified spatial scene.
IIT translates these experiential truths into physical terms through intrinsic causal power. A system exists for itself to the degree that its parts affect one another over time. By looking at how components interact, scientists can compute a transition probability matrix. This calculation yields a single number, represented by the Greek letter phi. A ceramic teapot has a phi near zero because its fired molecules remain fixed and exert little internal change on each other. A mammalian brain, with tens of thousands of connections looping back into every neuron, generates enormous phi. The complex unfolded structure of this causal power is identical to the conscious experience itself.
Boundaries and the Maximum of Phi
Unlike classical panpsychism, which struggles to explain why everything does not combine into one giant cosmic soup, IIT sets clear physical boundaries. Consciousness exists only where phi reaches a mathematical maximum. This principle answers why two people talking in a room do not form a shared super-mind. The causal feedback inside an individual skull vastly outstrips the slow trickle of speech exchanged across the air. The internal brain circuits claim the maximum, leaving the collective pair with no unified awareness of its own.
Medical history confirms these hard boundaries. Surgeons who severed the corpus callosum in severe epilepsy cases split the brain's 200 million connecting fibers. This radical cut produced two separate conscious subjects inside a single skull. The talking left hemisphere knew nothing about objects placed unseen in the patient's left hand, while the non-verbal right hemisphere recognized them immediately. If researchers were to reverse this process and bridge two human brains with millions of high-density artificial wires, IIT predicts a dramatic threshold. At the exact moment the joint phi exceeded each separate brain's phi, both individuals would vanish. In their place, a single new mind would wake up, looking out through four eyes.
The Ontological Shock
This tidy physicalist framework faced a serious test when Koch attended a traditional Santo Daime ceremony in Bahia, Brazil. Stepping outside his laboratory routines, he drank the psychedelic brew ayahuasca and fell into an ecstatic state that felt like tapping into a universal mind at large. The boundary between the observer and the observed dissolved, echoing Arthur Schopenhauer's description of the pure, will-less subject of knowledge.
The experience left Koch in an unresolved metaphysical tension. Mainstream neuroscience treats the brain as a generator or a mirror. Under this view, powerful drugs simply scramble neural circuits, showing only what strange tricks a physical organ can pull off under stress. Yet the sheer vividness of entering a universal mind mirrors Aldous Huxley's filter hypothesis, where the physical brain normally throttles down a boundless reality. Koch remains skeptical of claims that flatline brains can experience out-of-body awareness, noting how unreliable human timekeeping becomes after cardiac arrest. Still, he insists that true science must remain open to anomalies rather than ignoring inconvenient facts.
Escaping the Gravity of the Ego
Letting go of the ego proves remarkably difficult. Koch compares ordinary selfhood to living in a strong gravitational well. From childhood to old age, humans remain trapped in an anxious habit of self-monitoring, constantly asking what every event means for their status, security, and future. Attempting to force an ego-death experience often backfires, throwing people into panic and bad trips when the instinct for survival fights back.
Yet when complete surrender occurs, the results run deep. Following his encounter with 5-MeO-DMT, Koch noticed that the late-night existential dread of death that had haunted him for decades had vanished entirely. Quoting the ecstatic second act of Richard Wagner's opera Tristan und Isolde, he points to the lovers' wish to dissolve their personal names and merge into one reality: 'Then I myself am the world.' Stripping away the self does not end reality. It reveals that awareness was the primary fact of existence all along.